In the art of snowplows which are used for clearing roadways and the like, considerable effort has been directed toward designing snowplow devices which are aimed at solving a pervasive problem; namely, clearing as much snow and slush as possible from the roadway while at the same time not damaging the road surface and not allowing irregularities in the road surface to damage the snowplow device.
Several different approaches have been tried. In one approach, a motor vehicle is provided with two separate and distinct means for removing snow and slush. Snow is removed by a scraper blade positioned somewhat above the road surface providing a clearance between the blade and the road. Slush is removed by a motor powered rotary brush whose bristles are disposed radially around a central, rotating axis, and which contact the road surface tangentially. This dual approach is complex and expensive requiring a separate scraper and separate motorized rotary brush.
In a second approach to solve the problem, a resilient, relatively soft rubber strip is attached to the lower edge of a plow blade. This strip contacts the road surface, scraping it and resiliently yielding to surface irregularities. Both snow and slush are removed simultaneously. The relatively soft rubber, however, is in constant contact with the road surface, at relatively high speed, and undergoes rapid wear and must be replaced often.
In a third approach, the entire plow blade, not just the leading edge, responds to surface irregularities. The entire plow blade is pivoted so that its leading edge changes from a sharply acute cutting angle to a broader angle allowing the leading edge to ride over an obstruction in the roadway. When the obstruction is passed, a spring action reorients the entire plow blade so that the leading edge returns to the sharply acute cutting angle. This approach requires a complex support structure for the entire plow blade. Furthermore, it requires a heavy duty spring-loaded device to return the blade to normal position.
Finally, another present approach to solve the problem of maintaining the plow blade in close contact with the road surface while simultaneously yielding to and riding over road surface irregularities is found in a hard plastic strip attached to the leading edge of a plow blade. The hard plastic strip is hard enough to maintain an acute cutting angle of the leading edge under normal circumstances, and it is flexible enough to yield to relatively immovable road surface irregularities, such as manhole covers. However, more easily moved surface irregularities, such as uneven borders between the original road surface and potholes, would be susceptible to plow blade damage because of the relatively acute cutting angle of the hard plastic strip. Another disadvantage of the hard plastic strip is evidenced when the hard plastic strip does yield to an immovable surface irregularity in that the strip does not maintain close contact with the sides of the obstruction. For example, a cylindrical obstruction would cause the hard plastic strip to yield in the geometrical outline of a parabola; it must stretch partially horizontally in order to yield to a vertical obstruction. The open space between the vertical wall of the cylinder and the parabolic outline of the hard plastic strip as it yields to the cylindrical obstruction would allow snow and slush to be missed by the plow blade, and pass under the blade.
In view of the above deficiencies and inadequacies of present snow plow devices, one object of the invention is to provide an attachment for a snow plow which solves the problem of close contact with the road surface while at the same time yielding to and riding over road surface irregularities.
A second object of the invention is to provide a brush attachment for a snow plow which does not require a separate motive source for its operation.
A third object of the invention is to provide a road surface brush that has a hardness greater than a typical road surface and will, therefore, be long-lasting.
A fourth object of the invention is to eliminate the need for a complex support structure for a plow blade which causes the entire plow blade to yield to road surface irregularities in order to broaden the cutting angle.
A fifth object of the invention is to provide a snow plow brush attachment whose bristles readily conform to the outline shape of the surface irregularities thereby preventing snow and slush from passing readily under the blade.
A sixth object of the invention is to provide a road surface contacting brush whose bristles have a hardness greater than ice.
A seventh object of the invention is to provide sharp bristles which assist the snow and slush removal process by cutting and pressure melting ice.
An eighth object of the invention is to provide a device for close contact with a road surface while at the same time pressing and brushing down against surface irregularities rather than scraping and shaving them off.
These and other objects are accomplished by the invention as described below.